Circular stair with central support and disc spacers between treads

ABSTRACT

A circular stair comprising a central vertical support member of uniform cross-section and a series of treads with inner end portions that fit around the support member and extend horizontally from it. Disc-like spacers fit around the support member and between each pair of adjacent treads which are angularly spaced apart with respect to the central support member. Means are provided for applying a permanent compressive load on the spacers and treads from the ends of the central support to increase the load carrying capacity of the treads.

United StatesPatent Allen 1 July 4, 1972 541 CIRCULAR STAIR WITH CENTRAL 1,726,133 8/1929 Wilson ..52 1s7 SUPPORT AND DISC SPACERS 3,114,941 12/1963 Blum ....52/182 BETWEEN TREADS 3,418,770 12/1968 Allmand ..52/187 [72] Inventor: Kenneth M. Allen, 2301 South El Camino FORElGN PATENTS OR A T N Road Mate", 94403 233,229 4/1964 Austria ..52/182 [22] Filed: July 17, 1970 643,058 7/1962 ltaly ..52/187 [21] Appl'No': sssn Primary ExaminerHenry C. Sutherland Assistant Examiner-Leslie A. Braun 52 us. or ..52/187, 52 191 ym Wickersham and Erickson [51] lnt.Cl E04t11/00,E04f11/18 [58] Field of Search ..182/52; 52/182, 184, 185,187, [57] ABSTRACT 52,191 A circular stair comprising a central vertical support member 56] References Cited of uniform cross-section and a series of treads with inner end portions that fit around the support member and extend UNITED STATES PATENTS horizontally from it. Disc-like spacers fit around the support member and between each pair of adjacent treads which are 215,166 5/1879 Royce ..52/l85 a l fl Spaced apart with respect to the central Support RleSCk member Means are provided for a permanent com. 400,470 4/1889 Marshall-H M52/184 pressive load on the spacers and treads from the ends of the 5801262 4/ 1897 YF central support to increase the load carrying capacity of the 705,794 7/1902 Snider... ....52/187 treads 839,846 1/1907 Holden ....52/187 1,547,254 7/1925 McClure ..52/187 9 Claims, 7 Drawing Figures PATENTEDJUL '4 1912 3.673 7'52 sum 1 or 2 EN TOR. KENNETH ALLEN hm FLwM ATTORNEYS PATENTEUJHL "4 I972 3.6 73 .7 52

sum 2 or 2 lNVEiSI} OR. KENNETH M. ALLEN ATTOR'NEYS CIRCULAR STAIR WITH CENTRAL SUPPORT AND DISC SPACERS BETWEEN TREADS This invention relates to an improved circular stair construction which can be prefabricated and packaged as a kit and subsequently assembled on the job site with a minimum of labor and expense. 1

Circular stairs have been widely used in homes, buildings, ships and other places particularly where the most efficient utilization of space is important. I-leretofore, manufactured or prefabricated stair assemblies were almost universally of a metal construction and comprised generally a central support column with treads extending horizontally therefrom in a helical pattern. With such prior stair constructions, the treads were fixed to the central column by welding or by some type of fasteners such as rivets or bolts and consequently were expensive, generally unattractive and often required excessive space for installation. Moreover, such circular stair assemblies heretofore devised were generally fabricated and assembled in the shop or factory and then transported to the job site for installation. Often this installation was laborious and time con suming because the prefabricated stair assembly was heavy, difficult to maneuver, and adjust in size to accommodate variations in surrounding structure.

A general object of the present invention is to provide a circular stair assembly that solves the aforesaid problems.

Another object of my invention is to provide a circular stair assembly that can be erected rapidly on a job site by relatively unskilled labor and without special tools.

Another object of the present invention is to provide a circular stair assembly that is attractive in appearance, adaptable to a wide variety of constructions and requires relatively less space than circular stair assemblies heretofore devised.

Another object of the present invention is to provide a circular stair that is strong, durable and also particularly well adapted for ease and economy of manufacture.

Another object of the present invention is to provide a circular stair that can be adjusted to some degree in size on the job site to accommodate variations in the supporting structure to which the stair is to be attached such as the distance between floor levels.

The aforesaid and other objects are accomplished by a circular stair comprising a central vertical support member of uniform cross-section with a series of treads having a fairly wide inner portion that fits around the support member. Disclike spacers that also fit-around the support member are provided between each pair of adjacent treads. The treads and intervening spacersare connected together by elongated pins so as to be angularly spaced apart in a helical arrangement along the central support member. A railing connects the treads together at their outer ends, and means are provided to provide a compressive load on all of the spacers and treads from the ends of the central support so that the treads are firmly anchored at one end.

Other objects, advantages and features of my invention will become apparent from the following detailed description of one embodiment thereof presented with the accompanying drawing, in which:

FIG. 1 is a view in elevation showing a circular stair embodying the principles of the present invention;

FIG. 2 is a plan view of the circular stairs shown in FIG. 1;

FIG. 3 is an enlarged fragmentary view partially in section showing the circular stair of FIG. 1 in greater detail;

FIG. 4 is a view in section taken along the line 44 of FIG.

FIG. 5 is a view in section taken along the line 5-5 of FIG.

FIG. 6 is another fragmentary view in elevation showing a portion of my circular stair with railing attached; and

FIG. 7 is an enlarged view in section taken along the line 7-7 of FIG. 1 showing a pair of treads in plan view.

Referring to the drawing, FIGS. 1 and 2 show a circular stair l0 embodying the principles of the present invention as viewed when assembled and installed between a lower floor 12 and an upper floor 14. In general, it comprises a vertical support or column 16 from which a series of stairs or treads 18 extend horizontally. The treads are attached at their inner ends to the vertical column and at their outer ends they are connected together by a hand railing 66.

The vertical support 16 shown in the drawings is a cylindrical member of high columnar strength such as a metal pipe. It may, however, be a solid metal, wood or concrete member and it may have any uniform cross-section, although the preferred cross-section is circular. At its lower end the support has a flange 22 which can be bolted or otherwise fastened directly to the lower floor 12 (FIG. 4). The upper end of the support has a fitting with a flange 24 that may be secured in a 7 similar manner to a suitable portion of the site structure such As shown in FIG. 3, which illustrates an enlarged fragmentary portion of the stair assembly 10, the treads 18 are held a predetermined vertical distance apart by annular spacers 30 that fit around the central support. These spacers preferably have a circular shape with a central opening 32 slightly larger than the diameter of the central support 16. Preferably, the spacers are made of some inexpensive material such as plywood or plastic having good compressive strength and durability and they generally have the same thickness (e.g. threefourths inch) so that a like number can be used to separate each adjacent pair of treads. However, spacers with a different thickness can be used wherever the tread spacing is to be varied or where it becomes necessary to change the distance between treads to adjust the level of the uppermost tread with respect to the joists or some other anchoring structure.

Each tread 18 in plan form, as seen in FIG. 7, has a generally pie-shaped configuration with a width at its outer edge that decreases radially inwardly until it reaches an inner end portion 34 having a constant width that is equal to or slightly greater than the diameter of the spacers 30. These treads may be made of any suitablematerial with sufficient strength such as wood. A particularly satisfactory construction, from the standpoint of strength and durability as well as appearance, are treads made of wood pieces that are glued together. The edge 36 of the inner end portion 34 of each tread preferably is semi-circular with a radius somewhat greater than that of the spacers, and the geometric center of this semi-circular edge is also the center of an opening 38 which is only slightly larger than the central column. Thus, the central column 16 extends through the tread openings 38 as well as the openings 32 through all of the spacers.

To achieve the spiral stair arrangement each tread is positioned angularly a certain number of degrees with respect to the tread below around the central support. This positioning of the treads is achieved automatically during the assembly of the stair by means of two holes 40 and 42 that are drilled in the inner end portion 34 of each tread. On every tread these two holes are spaced radially from the geometric center of the opening and an equal angular distance apart (e.g. 21). Each spacer is also provided with one hole 44 which is spaced radially from its center at the same distance as the tread holes 40 and 42. Each tread is fixed to the tread below and to the spacers between by an elongated cylindrical pin member 46.

As shown in FIGS. 3 and 7, for each pair of adjacent treads,

the pin 46 fits in the hole 40 of the uppermost tread 18, extends through the holes 44 of stacked spacers below it, and fits in the arcuately spaced hole 42a of the lowermost tread 18a, thereby holding the treads the proper angular position with respect to each other.

The hand railing for the stair 10 is comprised of rod-like members 52 that extend upwardly through openings 54 and 56 near each outer end corner of each tread. As shown in FIG. 6, one upright rod member has an enlarged foot portion 58 or bolt head at its lower end which engages the floor 12. A sleeve spacer 60 around this rod member extends between the foot member and the underside of the lower tread 18a to help support it. On the upper side of the lower tread a nut 62 is threaded to the rod member 52 and is taken up firmly against a washer that bears on the tread. The upper end of the rod-like member has a ring-like fitting 64 for retaining a suitable railing member 66. With the treads spaced and positioned with respect to each other as previously described, as shown in FIG. 6, the hole56 in the leading edge comer of one tread is aligned vertically with a hole 54 near the trailing edge of the next tread above. Thus, an upright rod member 52 may be secured by a nut 68 at its lower end and it extends through two treads 18a and 18 before continuing upwardly to the curved railing member. On each such rod member between each pair of treads is a sleeve spacer 70 to help support them at the proper distance apart, and threaded to the rod member 52 on the upper side of the upper thread is a retaining nut 72 and washer.

Other forms of hand railings and supports therefore could be provided within the scope of the invention. For example, an alternate baluster detail is shown on the right-hand side of the tread 18 illustrated in FIG. 6. Here, the rod-like member 52a extends through an annular ring member 74 on the upper side of the tread 18b. This ring is tapped internally to receive the lower end of a tubular stanchion 76 which extends upwardly to support the hand railing. I

The assembly and installation of my stair is unusually simple and-can be easily accomplished by one relatively unskilled workman. The first step is to attach the lower flange member 22 to the central post or column 16. At the job site, the initial series of spacers 30 are installed on the central support member and a first or bottom tread 18a is placed on top of these first spacers. Now, a second series of spacers is placed on the pipe and the second tread member 18 is also installed.

In plan view, the upper tread 18 is rotated ahead of the lowermost tread 18a until the first hole 40 on the upper tread matches the second hole 42a on the lower tread as well as the holes 44 in the spacers 30 in between. An elongated pin 46 is placed through these aligned holes to hold these first two treads in the proper position with respect to each other. Now, another series of spacers are placed over the central column followed by the third tread, and the hole aligning and pin insertion procedure is repeated. All of the remaining treads and spacers are installed in the same manner. Before the spacers and treads are placed in the central support members, it is installedin its proper location on the lower floor. When the final tread is to be secured, spacers of varying thickness may be used to shim the uppermost tread to just the right position with respect to an upper floor level. Before final installation of the central support by its upper flange, a compression nut 740 on the upper end of the central support is turned to force the flange member 24 to compress the complete stack of spacers and treads against the bottom flange 22 supported on the lower floor l2. Sufi'icient compressive force is thus applied to secure the treads tightly between the spacers and the area of the spacers is sufficient to create a considerable bearing force on the treads at their inner ends. Once the maximum compression force on the spacers and treads has been accomplished, the upper end of the support column is secured to the building structure such as to a cross member 26 between a pair of joists 28.

If desired, the hand railing 66 may be installed in the manner already described. This railing and its supporting upright members 52 are not necessary for supporting the treads, but a railing is desirable in most instances from the standpoint of safety.

it should be apparent that the present invention provides a highly versatile, yet relatively inexpensive and easy to install circular stair. It can readily be made in different sizes to accommodate various floor spacings and since it requires a relatively small amount of floor space it is particularly adaptable for dwellings where space is a premium.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without delparting from the spirit and scope of the inventron. The disc osures and the description herem are purely illustrative and are not intended to be in any senselimiting.

I claim:

1. A circular stair comprising:

an elongated central vertical support member of uniform cross section;

a series of treads extending horizontally from said support member each having an inner end portion with an opening that fits closely around said support member;

a plurality of broad flat spacer disks extending around said support member and located between each pair of adjacent treads each disk having an opening fitting closely around said support member;

the inner end portion of each tread having first and second holes, said holes being located at the same radial distance from the axis of said support outwardly of the opening in the tread and being circumferentially spaced from each other wherein the first hole is the leading hole and the second hole is the trailing hole;

said spacer disks each having a single hole located radially from the axis of said support the same distance as said first and second holes and outwardly of said opening in each disk;

the trailing hole of each upper tread of a pair of adjacent treads being vertically aligned with the leading hole of each lower tread of each said pair of adjacent treads and with said single hole of each spacer disk between each said pair of adjacent treads and a single pin passing into said holes in each said pair of adjacent treads; and

means for applying a compressive force on the spacers and treads on said central support to hold said treads firmly at one end.

2. The circular stair as described in claim 1 wherein substantially all of said spacer disks are plywood members of uniform thickness.

3. The circular stair as described in claim 2 wherein said spacer disks are circular in shape with a uniform diameter and said treads have an inner end portion of uniform thickness and a width that is not less than the diameter of said plywood spacer members.

4. The circular stair as described in claim 3 wherein said treads are formed from laminated wood members.

5. The circular stair as described in claim 1 wherein said means for applying a compressive force comprises a flanged fitting slidably attached around the upper end of said support member just below a threaded end portion thereon, and an adjustable nut on said threaded end portion bearing on said flanged fitting.

6. A circular stair assembly as described in claim 1 comprismg railing means interconnecting said tread members at their outer end portions.

7. The circular stair assembly as described in claim 6 wherein said railing means comprises rod means having a lower end adapted to be supported below a lowermost tread member and extending upwardly through an opening near the trailing edge thereof, and additional rod means extending upwardly through vertically aligned openings located near the leading edge of each lower tread and the trailing edge of the tread directly above.

8. The circular stair assembly as described in claim 6 wherein said support member has an externally threaded portion at its upper end and said means for applying a compressive force comprises a flanged member and a nut member on said threaded portion for pressing said flanged member vertically against said annular members and said tread members.

9. The circular stair assembly as described in claim 6 wherein said support member is a metal pipe with a flanged end fitting at its lower end.

t i l l il 

1. A circular stair comprising: an elongated central vertical support member of uniform cross section; a series of treads extending horizontally from said support member each having an inner end portion with an opening that fits closely around said support member; a plurality of broad flat spacer disks extending around said support member and located between each pair of adjacent treads each disk having an opening fitting closely around said support member; the inner end portion of each tread having first and second holes, said holes being located at the same radial distance from the axis of said support outwardly of the opening in the tread and being circumferentially spaced from each other wherein the first hole is the leading hole and the second hole is the trailing hole; said spacer disks each having a single hole located radially from the axis of said support the same distance as said first and second holes and outwardly of said opening in each disk; the trailing hole of each upper tread of a pair of adjacent treads being vertically aligned with the leading hole of each lower tread of each said pair of adjacent treads and with said single hole of each spacer disk between each said pair of adjacent treads and a single pin passing into said holes in each said pair of adjacent treads; and means for applying a compressive force on the spacers and treads on said central support to hold said treads firmly at one end.
 2. The circular stair as described in claim 1 wherein substantially all of said spacer disks are plywood members of uniform thickness.
 3. The circular stair as described in claim 2 wherein said spacer disks are circular in shape with a uniform diameter and said treads have an inner end portion of uniform thickness and a width That is not less than the diameter of said plywood spacer members.
 4. The circular stair as described in claim 3 wherein said treads are formed from laminated wood members.
 5. The circular stair as described in claim 1 wherein said means for applying a compressive force comprises a flanged fitting slidably attached around the upper end of said support member just below a threaded end portion thereon, and an adjustable nut on said threaded end portion bearing on said flanged fitting.
 6. A circular stair assembly as described in claim 1 comprising railing means interconnecting said tread members at their outer end portions.
 7. The circular stair assembly as described in claim 6 wherein said railing means comprises rod means having a lower end adapted to be supported below a lowermost tread member and extending upwardly through an opening near the trailing edge thereof, and additional rod means extending upwardly through vertically aligned openings located near the leading edge of each lower tread and the trailing edge of the tread directly above.
 8. The circular stair assembly as described in claim 6 wherein said support member has an externally threaded portion at its upper end and said means for applying a compressive force comprises a flanged member and a nut member on said threaded portion for pressing said flanged member vertically against said annular members and said tread members.
 9. The circular stair assembly as described in claim 6 wherein said support member is a metal pipe with a flanged end fitting at its lower end. 